This invention relates to an electron beam-excited ion beam source in which ions are produced by electron beam irradiation.
Ion beam sources have been used to etch semiconductor substrates. In order to efficiently etch the semiconductor substrates without causing large damage to the substrates, a high current and low energy ion beam is needed. However, the high current and low energy ion beam could not be obtained by conventional sources far. In the known ion beam sources, the ion beam currents low energy are below 10 mA/cm.sup.2. One of the known ion beam sources is disclosed by J. Uramoto in Research Report of Institute of Plasma Physics, Nagoya University, Nagoya, Japan, IPPJ-395 (1979).